1. Field of the Invention
This invention relates to the atomization of liquids and in particular it concerns novel methods and apparatus for forming atomized liquid droplets of minimal size.
2. Description of the Related Art
U.S. Pat. No. 5,164,740 describes a vibrating plate atomizing device in which liquid which is supplied to one side of a vibrating orifice plate, passes through orifices in the plate and becomes atomized and ejected from the opposite side of the plate. Other U.S. patents which describe similar devices are U.S. Pat. No. 5,586,550, U.S. Pat. No. 5,297,734 and U.S. Pat. No. 6,296,136 B1.
Such devices may be used to disperse liquids, such as fragrances and insecticides into the atmosphere. When such liquids are formed into small droplets and ejected as droplets into the atmosphere, their high surface area to volume ratio improves their ability to evaporate. While it is preferred that each droplet evaporates entirely before falling back onto an adjacent surface, this does not always happen due to various factors, one being that the size of many of the droplets is so large that they do not have time to fully evaporate before reaching the adjacent surface.
The present invention helps to minimize the amount of unevaporated liquid from a vibrating plate atomizing device which falls back toward an adjacent surface.
According to one aspect of the invention, there is provided a novel method of generating droplets of minimal diameter by means of a vibratory atomization plate to which a liquid is delivered. This novel method involves the steps of treating the surface of the plate from which droplets are ejected during atomization to minimize liquid accumulation on said surface, and supplying the liquid to the plate while vibrating it to atomize the liquid.
According to a further aspect of the invention, there is provided a novel atomization device for converting a liquid into droplets of minimum diameter and ejecting said droplets into the atmosphere. This novel device comprises an atomization plate coupled to an actuator to be vibrated by the actuator and a liquid supply system arranged to supply liquid to the plate as it is being vibrated. The plate has a surface, from which droplets are ejected, which has been treated to minimize accumulation of liquid.
It has been found that by providing the vibrating plate with a finish on its ejection surface that eliminates or at least minimizes accumulation or buildup of liquid, the plate can eject droplets which are smaller and which are thrown up top a greater height than is possible with vibrating plates having conventional surface finishes.